Process of dissolving cellulose esters and cellulose ethers



Patented Feb. 24;, 1931 G'W-ESCHING-EN, 0F VIENNA, AUSTRIA, ASSIGNOR, BY' MESNE ASSIG-Nlri HADES PATENTS GORPQRATION, OF NEW YORK, N. Y., A CORPORATION (3F IIEW YORK TITS, TO

PROCESS OF DISSOLVING ESTERS AND CELLULOSE ETHERS No Drawing. Application filed March 18, 1925, S

This invention relates to a process of dissolving cellulose-esters and cellulose-ethers.

At present there are not any common terms, which clearly characterize the nature of the wood-oils (wood alcohol oils) obtained as residuary products of the distillation process of wood alcohol.

These oils remain after the methyl alcohol (Wood spirit) has been distilled off. As byproducts of the methyl-alcohol production are here in question, only those materials are to be here considered which serve for the production of raw-wood spirits, principally of wood leaved trees, but also certain lignites and peats. The raw wooden spirit (wood alcohol) contains besides methyl alcohol greater or smaller quantities of acetone, allyl alcohol, furfurol. ethyl alcohol, dimethyl acetate, pyroxanthine, as they are indicated in the British patent specification 28,613 of the year 1896. By the rectification of the raw wood alcohol which has for its object the manufacture of pure methyl alcohol byproducts are formed of essentially different composition, as frequently condensations and ring formations take place, so, for instance, trimethylacetaldehyde, methylethylketone, isovaleraldehyde, cyklopentanone, and several non-saturated alcohols, furan and pyrol compounds are formed, see Berichte der Deutschen Chem. Ges. 1923, page 2035 and 1924, page 1561.

Of course, the composition depends on the raw material which is used for the distillation fluctuating, and, therefore, also the dissolving property of these by-products is fluctuating.

These residuary products are preferably characterized as oils insoluble or only difficultly soluble in water and which remain as a residue during the distillation process. These oils are a brownish, keen smelling liquid, which has to be first subjected to a second distillation in order to render it for use as a solvent according to the presem invention. Such distillations are known and are used in the varnish industry.

According to the present invention the distillation temperature may be raised by direct heating till a temperature of 120 C. is

erial No. 18,577, and in Austria March 24, 1924.

reached, Without causing any detrimental restatements about the composition of the wood oils are available. Moreover t ie composition essentially depends on the Wood used for the charring 1 process. The following large groups of substances are contained in woodoils, viz. aldehydes, ketones, acetales, unsaturated heterocyclic bodies, saturated and unsaturated higher carbureted hydrogen, ester and small quantities of alcohols.

Of these combinations some can act as solvent. Such are for cellulose-ester or cellulose-ether for instance the lower l zetones, certain heterocyclic bodies, some esters and some alcohols. However, very few of these products are available, so that the same are not of any consequence in view of the other constituents forming non-solvents.

Thus the solvent ability can be obtained by the present entire mixture.

As proof ofthis it may be mentioned, that fractions can be separated which are complete non-solvents composition not known) and which on adding only a very small amount of another nolrsolvent (for instance ethyl-alcohol) become good solvents.

The following examples relate to an available wood oil and certain modifications are necessary when using wood-oil of another origin and character.

1. Nitrocellulose is dissolved in the whole distillation product or in single fractions.

2. Acetylcellulosc dissolves in the original distillation product. It does not dissolve in the distillation product till temperature of 120 C. is reached. It dissolves ver easily in the fractions up to 90 (1., dissolves very easily in the fractions up to 110 C. by adding very small amounts of methylated spirit or ethyl-alcohol. It does not dissolve in fractions above C. in the cold. Dissolves in the heat in the fractions above 100 C. when adding methylated spirit or ethylic alcohol. Can be dissolved with great difficulty in the fractions up to 90 C. when adding tetrachlorethane.

8. Ethyl-cellulose behaves very similar to the acetylcellulose.

In this manner solventsof different volatility can be combined, which is of the greatest importance in the film-industry.

Also different mixtures of cellulose-ester or cellulose-ether may be dissolved together in the same solvent.

The solvent according to the present invention is mainly used for producing films with a high dielectric constant or piercing resistance, such as for instance when constructing electric condensers. Of course also insulating varnishes may be composed on the base of cellulose-ester or ether of various compositions and duration of drying.

I claim l 1. The process of making solutions of cellulose derivatives which comprises dissolving a cellulose derivative, wherein the cellulose is in either linkage, in wood oil, said wood oil being the product resulting from the distillation at a maximum temperature of C. of residual oils obtained inthe initial distillation of wood.

2. The process of making solutions of cellulose derivatives which comprises dissolving a cellulose derivative, wherein the cellulose is in ether linkage, in wood oil fractions, said wood oil fractions being one of the fractions obtained by making suitable cuts in the product obtained from the distillation of residual oils obtained in the initial distillation of wood.

3. The process of making solutions of cellulose derivatives which comprises dissolving a cellulose derivative, whereinthe cellulose is in either linkage, in wood oil and additional known solvents, said wood oil being the product resulting from the distillation at a maximum temperature of 120 C. of residual oils obtained in the initial distillation of wood.

4. The process of making solutions of cellulose derivatives which comprises dissolving a cellulose derivative, wherein the cellulose is in ether linkage, in wood oil fractions and additional known solvents, said wood oil fractions being one of the fractions obtained by making suitable cuts in the product obtained from the distillation of residual oils obtained in the initial distillation of wood.

In testimony whereof I afiiX my si nature.

MAX ow-nscnin onn. 

